Filed of the Invention
The present invention relates to a method for producing a Group III nitride semiconductor light-emitting device having a reflective electrode on a p-type layer.
Background Art
In a flip-chip type Group III nitride semiconductor light-emitting device, an electrode (reflective electrode) serving as a reflective film is formed on a p-type layer to reflect light toward the rear surface of a substrate, thereby improving the light extraction efficiency. Ag or Ag alloy is widely used for the reflective electrode.
Ag is a material easy to cause migration. It is known that the reflective electrode is prevented from coming into contact with moisture by covering with a cover metal, thereby suppressing migration.
Japanese Patent Application Laid-Open (kokai) No. 2009-49266 discloses a light-emitting device having a first metal film made of Ag on the p-type layer, a dielectric film provided apart from the first metal film on the p-type layer, and a second metal film made of a metal not containing Ag, which covers the top of the first metal film, the dielectric film, and the p-type layer exposed between the first metal film and the dielectric film. The first metal film is covered with the second metal film so that the first metal film is isolated from the atmosphere, thereby preventing migration.
However, the cover metal is formed so as to cover the reflective electrode so that the cover metal is in contact with the p-type layer in the vicinity of the ends of the reflective electrode. The problem is that light extraction efficiency is deteriorated because light is absorbed by the cover metal at the ends.